If you need a prescription filled, be careful before ordering from an online pharmacy.

We all know that the price of prescription drugs is enough to give you a headache, but don't be so eager to get a price break that you end up with counterfeit drugs, advises the National Consumers League (NCL).

"Getting fooled by counterfeit drugs could mean wasting your money on ineffective medicine, but it could also mean taking grave health risks with drugs that aren't what they pretend to be," Linda F. Golodner, NCL president, said in a press release.

In a recent report by the General Accounting Office, the federal agency found many instances where Internet pharmacies -- most operating in foreign countries -- exhibited shaky business practices, including not requiring people to have a prescription to make purchases.

In its test of online prescription ordering, the GAO obtained 68 samples of 11 drugs -- each from a different pharmacy Web site in the United States, Canada or elsewhere. The GAO found fewer problems among pharmacies it contacted in Canada and the United States. But the GAO still found enough to make me quiver.

For example, the GAO got stiffed. The agency paid for but never received six drug orders totaling more than $700. In addition, some drugs were counterfeit, and others had return addresses on the packaging that, when traced, turned out to be private residences.

It turned out that 14 of the 68 pharmacy Web sites tested were already under investigation by regulatory agencies for such charges as selling counterfeit drugs or providing prescription drugs where no valid doctor-patient relationship existed. In some cases, foreign Internet pharmacies appeared to offer U.S. versions of brand-name drugs on their Web sites but attempted to substitute an alternative drug during the ordering process.

"Certain practices of Internet pharmacies may render it difficult for consumers to know exactly what they are buying," the GAO report concluded.

So how can you tell if you're dealing with a legitimate Web pharmacy? Here are signs of a suspicious online pharmacy, according to the National Association of Boards of Pharmacy (NABP), a professional association that represents boards of pharmacy in all 50 states and the District:

* Suspect e-pharmacies will dispense prescription medications without requiring you to mail in a prescription, or they may not contact your doctor to obtain a valid prescription orally. Some send you medication based solely on an online questionnaire without you having a pre-existing relationship with a doctor and the benefit of an in-person physical examination.

* If the online pharmacy doesn't have a toll-free phone number as well as a street address posted on its site, keep clicking. If the only means of communication between you and the pharmacy is by e-mail, your scam bells should be ringing. NABP says that illegal pharmacy sites frequently sell their customer lists to other illegitimate online businesses. So if you buy from a sham site, you could be marking yourself as a scam target.

* If a site does not advertise the availability of pharmacists for medication consultation, it should be avoided. Legitimate sites allow consumers to contact pharmacists if they have questions about their medications.

* Be leery of online pharmacies that sell a limited number of medications. Although pharmacies may not sell every medication available in the United States, those that specialize in medications that treat sexual dysfunction or assist in weight loss, for example, may not be operating legitimately.

Pfizer Inc., the maker of Viagra, announced recently that it was going to aggressively pursue legal action against dozens of illegitimate online pharmacies that sell counterfeit Viagra.

Those illegal Web sites often claim that you can buy Viagra from them, then send consumers a counterfeit drug. Some sites promote a generic version of the drug. Pfizer says that's just not possible since there is no FDA-approved generic version of its drug.

There is one way to help identify a legitimate online pharmacy. Contact the NABP at www.nabp.net/vipps/intro.asp. On the site you will find the association's Verified Internet Pharmacy Practice Sites (VIPPS) program, which is a free service that allows consumers to check the legitimacy of an online pharmacy. Always look for the VIPPS seal and then verify that the site is legit with NABP.

As demand and cost for prescription drugs rise, many consumers will be turning to the Internet to make their pharmaceutical purchases. Making sure the pharmacy is legitimate is an essential first step to doing this safely.

As for whether the drugs themselves are counterfeit, the NCL Web site (www.nclnet.org) offers some tips: First, know the size, shape, color and taste of your prescription pills. Check any differences with your doctor. Also, check for altered or unsealed containers, or changes in packaging or label.

But searching for drugs at a discount without first checking out the online pharmacy could damage not just your finances, but also your health.

Michelle Singletary discusses personal finance Tuesdays on NPR's "Day to Day" program and online at www.npr.org. Readers can write to her at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or by e-mail at singletarym@washpost.com. Comments and questions are welcome, but please note that they may be used in a future column, with the writer's name, unless a specific request to do otherwise is indicated.